A vehicle grill is typically located at a front of a vehicle, and can be configured to provide an opening through with intake air is received from outside of the vehicle, such as a grill opening or bumper opening. Such intake air may then be directed to an engine compartment of the vehicle to assist the vehicle's cooling system in cooling the engine, transmission, and other such components of the engine compartment. Such air flow via the grill may add aerodynamic drag when the vehicle is in motion. Accordingly, some grills may employ grill shutters to block such air flow, thus reducing aerodynamic drag and improving fuel economy. Closed grill shutters may also provide a faster powertrain warm-up which may improve fuel economy since there is less friction, and may improve the performance of the passenger compartment heater. However, such shutters also reduce the air flow through the radiator and other components for cooling purposes. Thus, traditional operation of such shutters includes opening the shutters partially and/or cycling the shutters open and closed to provide appropriate air flow based on cooling demands.
One example of operating vehicle shutters includes operating the shutters based on a temperature of the engine or a temperature of the coolant, so as to provide appropriate air flow for cooling purposes. As an example, a temperature sensor may detect the cooling water temperature of the engine, and calculate a time-dependent progression of the temperature change, and based on this, determine the opening angle to be set for the shutters. The inventor of the present application has recognized a problem in such previous solutions, in that such shutter operation may increase aerodynamic drag, and thus be at the expense of fuel economy.
In one example, some of the above issues may be addressed by operating the shutters not only based on cooling system demands, but also considering conditions where an increase in aerodynamic drag does not cause any fuel economy loss, such as during deceleration. Thus, a method of adjusting a grill shutter system for a vehicle is disclosed herein, which comprises adjusting opening of one or more grill shutters located at a front end opening of the vehicle in response to a non-driven vehicle condition. A non-driven vehicle condition includes when the vehicle is not being driven by the engine/powertrain, such as during a deceleration condition, a braking condition (during deceleration or acceleration), etc. In this way, a driver may already be “throwing away” energy, for example to the brakes, and thus opening the shutters in response to a non-driven vehicle condition can provide cooling that is not at the expense of fuel economy. Further, by pre-cooling the powertrain components to lower temperatures during a non-driven vehicle condition, an amount of shutter opening (e.g., a degree of shutter opening and/or a duration of shutter opening) during later, driven vehicle conditions, can be reduced. For example, during later acceleration, opening of the shutters can be delayed. As another example, during later acceleration, even if the opening timing of the shutters is not delayed, the degree of opening may be reduced. Further, grill shutters may be opened during a non-driven vehicle condition when cooling is desired, to avoid reducing the benefits of closed grill shutters described above (faster powertrain warm-up, improved performance of the passenger compartment heater, etc.).
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.